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1.
Artículo en Inglés | MEDLINE | ID: mdl-32000493

RESUMEN

TiO2 is a good photoanode material for water oxidation to form O2; however, UV light (λ < 400 nm) is necessary for this system to operate. In this work, cobalt species were introduced onto a rutile TiO2 thin film grown on a fluorine-doped tin oxide (FTO) substrate for visible-light activation of TiO2 and to construct water oxidation sites. TiO2 thin films were prepared on the FTO surface by the thermohydrolysis of TiCl4, followed by annealing at 723 K in air; the loading of the cobalt species was achieved simply by immersing TiO2/FTO into an aqueous Co(NO3)2 solution at room temperature, followed by heating at 423 K in air. Physicochemical analyses revealed that the cobalt species deposited on the TiO2 film was α-Co3(OH)4(NO3)2 and that the cobalt-modified TiO2 thin-film electrode had a visible-light absorption band that extended to 700 nm due to interfacial electron transitions from the cobalt species to the conduction band of TiO2. Upon anodic polarization in the presence of visible light, the cobalt-modified TiO2 thin-film electrode generated an anodic photocurrent with an onset potential of +0.1 V vs RHE, which was consistent with that of pristine rutile TiO2. Product analysis during the controlled potential photoelectrolysis in the presence of an applied bias smaller than 1.23 V under visible light showed that water oxidation to O2 occurred on the cobalt-modified TiO2/FTO. This study demonstrates that a visible-light-driven photoelectrochemical cell for water oxidation can be constructed through the use of earth-abundant metals without the need for a complicated preparation procedure.

2.
Chem Asian J ; 15(4): 540-545, 2020 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-31912639

RESUMEN

The Pb-V oxyhalide apatite compounds Pb5 (VO4 )3 X (X=F, Cl, Br, I) were successfully synthesized using a facile solution method and studied with respect to their structural/optical characteristics and electronic band structures. UV-visible diffuse reflectance spectroscopy, electrochemical analysis and first-principles calculations showed that the synthesized apatites behaved as n-type semiconductors, with absorption bands in the UV-visible region that could be assigned to electron transitions from the valence band to a conduction band formed by hybridized V 3d and Pb 6p orbitals. Among the apatites examined, Pb5 (VO4 )3 I had the smallest band gap of 2.7 eV, due to an obvious contribution of I 5p orbitals to the valence band maximum. Based on its visible light absorption capability, Pb5 (VO4 )3 I generated a continuous anodic photocurrent under visible light (λ>420 nm) in a solution of 0.1 m NaI in acetonitrile.

3.
Dalton Trans ; 48(42): 15778-15781, 2019 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-31617522

RESUMEN

Although Zn-based binary semiconductors such as ZnO and ZnS are photocatalytically unstable toward water oxidation, we found that mixed-anionization successfully addressed this issue. This report shows that an oxysulfide SrZn2S2O functions as a photocatalyst to reduce and oxidize water under band-gap irradiation without noticeable decomposition of the material.

4.
J Am Chem Soc ; 141(43): 17158-17165, 2019 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-31588742

RESUMEN

Mixed-anion compounds (e.g., oxynitrides and oxysulfides) are potential candidates as photoanodes for visible-light water oxidation, but most of them suffer from oxidative degradation by photogenerated holes, leading to low stability. Here we show an exceptional example of a stable, mixed-anion water-oxidation photoanode that consists of an oxyfluoride, Pb2Ti2O5.4F1.2, having a band gap of ca. 2.4 eV. Pb2Ti2O5.4F1.2 particles, which were coated on a transparent conductive glass (FTO) support and were subject to postdeposition of a TiO2 overlayer, generated an anodic photocurrent upon band gap photoexcitation of Pb2Ti2O5.4F1.2 (λ <520 nm) with a rather negative photocurrent onset potential of ca. -0.6 V vs NHE, which was independent of the pH of the electrolyte solution. Stable photoanodic current was observed even without loading a water oxidation promoter such as CoOx. Nevertheless, loading CoOx onto the TiO2/Pb2Ti2O5.4F1.2/FTO electrode further improved the anodic photoresponse by a factor of 2-3. Under AM1.5G simulated sunlight (100 mW cm-2), stable water oxidation to form O2 was achieved using the optimized Pb2Ti2O5.4F1.2 photoanode in the presence of an applied potential smaller than 1.23 V, giving a Faradaic efficiency of 93% and almost no sign of deactivation during 4 h of operation. This study presents the first example of photoelectrochemical water splitting driven by visible-light excitation of an oxyfluoride that stably works, even without a water oxidation promoter, which is distinct from ordinary mixed-anion photoanodes that usually require a water oxidation promoter.

5.
ACS Appl Mater Interfaces ; 11(39): 35702-35712, 2019 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-31532604

RESUMEN

In this study, graphitic carbon nitride (g-C3N4) nanosheets (CNns) were modified using polyaniline (PANI) codoped with an inorganic (hydrochloric acid, HCl) and an organic (phytic acid, PA) acid. Our results revealed that these samples exhibited extended visible-light absorption and a three-dimensional (3D) hierarchical structure with a large specific surface area. They also inhibited photoluminescence emission, reduced electrical resistance, and provided abundant free radicals, resulting in high photocatalytic performance. The PANI/g-C3N4 sample demonstrated outstanding photocatalytic activity of a Cr(VI) removal capacity of 4.76 mg·min-1·gc-1, which is the best record for the reduction of a 100 ppm K2Cr2O7 solution. Moreover, g-C3N4 coupled with PANI monotonically doped with HCl or PA did not demonstrate increased activity, suggesting that the codoping of HCl and PA plays a significant role in enhancing the performance. The improved photocatalytic activity of PANI/g-C3N4 can be attributed to the interchain and intrachain doping of PA and HCl over PANI, respectively, to create a 3D connected network and synergistically increase the electrical conductivity. Therefore, new insights into g-C3N4 coupled with PANI and codoped by HCl and PA may have excellent potential for the design of g-C3N4-based compounds for efficient photocatalytic reactions.

6.
Dalton Trans ; 48(32): 12272-12278, 2019 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-31339138

RESUMEN

An extremely large displacement of the indium site in In-S6 octahedra in LnOInS2 (Ln = La, Ce, and Pr) was found in synchrotron X-ray diffraction. LaOInS2 with off-center indium in In-S6 octahedra exhibited a wider optical band gap than CeOInS2 and PrOInS2 with on-center indium. Therefore, the electronic structure of LnOInS2 is governed by the indium site with an extremely large displacement. All LnOInS2 produced H2 gas under visible light irradiation in the presence of sacrificial electron donors.

7.
J Am Chem Soc ; 141(24): 9593-9602, 2019 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-31135147

RESUMEN

A push-pull organic dye and a cobaloxime catalyst were successfully cografted on NiO and CuGaO2 to form efficient molecular photocathodes for H2 production with >80% Faradaic efficiency. CuGaO2 is emerging as a more effective p-type semiconductor in photoelectrochemical cells and yields a photocathode with 4-fold higher photocurrent densities and 400 mV more positive onset photocurrent potential compared to the one based on NiO. Such an optimized CuGaO2 photocathode was combined with a TaON|CoO x photoanode in a photoelectrochemical cell. Operated in this Z-scheme configuration, the two photoelectrodes produced H2 and O2 from water with 87% and 88% Faradaic efficiency, respectively, at pH 7 under visible light and in the absence of an applied bias, equating to a solar to hydrogen conversion efficiency of 5.4 × 10-3%. This is, to the best of our knowledge, the highest efficiency reported so far for a molecular-based noble metal-free water splitting Z-scheme.

8.
Adv Mater ; 31(25): e1808205, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31066136

RESUMEN

CO2 reduction to carbon feedstocks using heterogeneous photocatalysts is an attractive means of addressing both climate change and the depletion of fossil fuels. Of particular importance is the development of a photosystem capable of functioning in response to visible light, which accounts for the majority of the solar spectrum, representing a kind of artificial photosynthesis. Hybrid systems comprising a metal complex and a semiconductor are promising because of the excellent electrochemical (and/or photocatalytic) activity of metal complexes during CO2 reduction and the ability of semiconductors to efficiently oxidize water to molecular O2 . Here, the development of hybrid photocatalysts and photoelectrodes for CO2 reduction in combination with water oxidation is described.

9.
J Exp Med ; 216(6): 1431-1449, 2019 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-31072819

RESUMEN

Regnase-1 (also known as Zc3h12a or MCPIP-1) is an endoribonuclease involved in mRNA degradation of inflammation-associated genes. Regnase-1 is inactivated in response to external stimuli through post-translational modifications including phosphorylation, yet the precise role of phosphorylation remains unknown. Here, we demonstrate that interleukin (IL)-17 induces phosphorylation of Regnase-1 in an Act1-TBK1/IKKi-dependent manner, especially in nonhematopoietic cells. Phosphorylated Regnase-1 is released from the endoplasmic reticulum (ER) into the cytosol, thereby losing its mRNA degradation function, which leads to expression of IL-17 target genes. By using CRISPR/Cas-9 technology, we generated Regnase-1 mutant mice, in which IL-17-induced Regnase-1 phosphorylation is completely blocked. Mutant mice (Regnase-1AA/AA and Regnase-1ΔCTD/ΔCTD ) were resistant to the IL-17-mediated inflammation caused by T helper 17 (Th17) cells in vivo. Thus, Regnase-1 plays a critical role in the development of IL-17-mediated inflammatory diseases via the Act1-TBK1-IKKi axis, and blockade of Regnase-1 phosphorylation sites may be promising for treatment of Th17-associated diseases.

10.
Inorg Chem ; 58(9): 6161-6166, 2019 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-30990027

RESUMEN

Two-dimensional (2D) layered oxynitrides are promising candidates as visible-light-driven photocatalysts, but the actual examples are rare because of the difficulty in synthesizing the 2D oxynitrides. Here a phase-pure layered perovskite, Rb2NdNb2O6N·H2O, that belongs to a tetragonal P4/ mmm space group was successfully synthesized by thermal ammonolysis of a mixture of layered RbNdNb2O7 and Rb2CO3, as revealed by synchrotron X-ray diffraction, elemental analyses, and atomic-scale electron microscopy observation. The synthesized Rb2NdNb2O6N·H2O had an absorption edge at around 500 nm and a sufficiently high conduction-band potential to allow for proton reduction. With modification by a platinum cocatalyst, Rb2NdNb2O6N·H2O became photocatalytically active for H2 evolution in the presence of triethanolamine as an electron donor under visible light (λ > 400 nm).

11.
Allergy ; 74(9): 1660-1674, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30891811

RESUMEN

Innate immune system quickly responds to invasion of microbes and foreign substances through the extracellular and intracellular sensing receptors, which recognize distinctive molecular and structural patterns. The recognition of innate immune receptors leads to the induction of inflammatory and adaptive immune responses by activating downstream signaling pathways. Allergy is an immune-related disease and results from a hypersensitive immune response to harmless substances in the environment. However, less is known about the activation of innate immunity during exposure to allergens. New insights into the innate immune system by sensors and their signaling cascades provide us with more important clues and a framework for understanding allergy disorders. In this review, we will focus on recent advances in the innate immune sensing system.

12.
Inorg Chem ; 57(21): 13953-13962, 2018 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-30295474

RESUMEN

A solid solution of GaN and ZnO (GaN:ZnO) is promising as a photocatalyst for visible-light-driven overall water splitting to produce H2. However, several obstacles still exist in the conventional preparation procedure of GaN:ZnO. For example, the atomic distributions of Zn and Ga are nonuniform in GaN:ZnO when a mixture of the metal oxides, i.e. Ga2O3 and ZnO, is used as a precursor. In addition, GaN:ZnO is generally prepared under a harmful NH3 flow for long durations at high temperatures. Here, a facile synthesis of GaN:ZnO with homogeneous atomic composition via a simple and safe procedure is reported. A layered double hydroxide (LDH) containing Zn2+ and Ga3+ was used to increase the uniformity of the atomic distributions of Zn and Ga in GaN:ZnO. We employed urea as a nitriding agent instead of gaseous NH3 to increase the safety of the reaction. Through the optimization of reaction conditions such as heat treatment temperature and content of urea, single-phase GaN:ZnO was successfully obtained. In addition, the nitridation mechanism using urea was investigated in detail. NH3 released from the thermal decomposition of urea did not directly nitride the LDH precursor. X-ray absorption and infrared  spectroscopies revealed that Zn(CN2)-like intermediate species were generated at the middle temperature range and Ga-N bonds formed at high temperature along with dissociation of CO and CO2.

13.
Proc Natl Acad Sci U S A ; 115(43): 11036-11041, 2018 10 23.
Artículo en Inglés | MEDLINE | ID: mdl-30297433

RESUMEN

Damage to intestinal epithelial cell (IEC) layers during intestinal inflammation is associated with inflammatory bowel disease. Here we show that the endoribonuclease Regnase-1 controls colon epithelial regeneration by regulating protein kinase mTOR (the mechanistic target of rapamycin kinase) and purine metabolism. During dextran sulfate sodium-induced intestinal epithelial injury and acute colitis, Regnase-1∆IEC mice, which lack Regnase-1 specifically in the intestinal epithelium, were resistant to body weight loss, maintained an intact intestinal barrier, and showed increased cell proliferation and decreased epithelial apoptosis. Chronic colitis and tumor progression were also attenuated in Regnase-1∆IEC mice. Regnase-1 predominantly regulates mTORC1 signaling. Metabolic analysis revealed that Regnase-1 participates in purine metabolism and energy metabolism during inflammation. Furthermore, increased expression of ectonucleotidases contributed to the resolution of acute inflammation in Regnase-1∆IEC mice. These findings provide evidence that Regnase-1 deficiency has beneficial effects on the prevention and/or blocking of intestinal inflammatory disorders.


Asunto(s)
Colon/metabolismo , Células Epiteliales/metabolismo , Mucosa Intestinal/metabolismo , Purinas/metabolismo , Regeneración/fisiología , Ribonucleasas/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Animales , Apoptosis/fisiología , Proliferación Celular/fisiología , Colitis/metabolismo , Modelos Animales de Enfermedad , Inflamación/metabolismo , Enfermedades Inflamatorias del Intestino/metabolismo , Ratones , Transducción de Señal/fisiología
14.
Beilstein J Org Chem ; 14: 1806-1812, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30112084

RESUMEN

Graphitic carbon nitride (g-C3N4) was synthesized by heating urea at different temperatures (773-923 K) in air, and was examined as a photocatalyst for CO2 reduction. With increasing synthesis temperature, the conversion of urea into g-C3N4 was facilitated, as confirmed by X-ray diffraction, FTIR spectroscopy and elemental analysis. The as-synthesized g-C3N4 samples, further modified with Ag nanoparticles, were capable of reducing CO2 into formate under visible light (λ > 400 nm) in the presence of triethanolamine as an electron donor, with the aid of a molecular Ru(II) cocatalyst (RuP). The CO2 reduction activity was improved by increasing the synthesis temperature of g-C3N4, with the maximum activity obtained at 873-923 K. This trend was also consistent with that observed in photocatalytic H2 evolution using Pt-loaded g-C3N4. The photocatalytic activities of RuP/g-C3N4 for CO2 reduction and H2 evolution were thus shown to be strongly associated with the generation of the crystallized g-C3N4 phase.

15.
J Am Chem Soc ; 140(24): 7437-7440, 2018 06 20.
Artículo en Inglés | MEDLINE | ID: mdl-29888920

RESUMEN

Efficient and selective photostimulated CO2-to-CO reduction by a photocatalytic system consisting of an iron-complex catalyst and a mesoporous graphitic carbon nitride (mpg-C3N4) redox photosensitizer is reported for the first time. Irradiation in the visible region (λ ≥ 400 nm) of an CH3CN/triethanolamine (4:1, v/v) solution containing [Fe(qpy)(H2O)2]2+ (qpy = 2,2':6',2'':6'',2''-quaterpyridine) and mpg-C3N4 resulted in CO evolution with 97% selectivity, a turnover number of 155, and an apparent quantum yield of ca. 4.2%. This hybrid catalytic system, comprising only earth abundant elements, opens new perspectives for solar fuels production using CO2 as a renewable feedstock.

16.
J Am Chem Soc ; 140(21): 6648-6655, 2018 05 30.
Artículo en Inglés | MEDLINE | ID: mdl-29733632

RESUMEN

Mixed anion compounds such as oxynitrides and oxychalcogenides are recognized as potential candidates of visible-light-driven photocatalysts since, as compared with oxygen 2p orbitals, p orbitals of less electronegative anion (e.g., N3-, S2-) can form a valence band that has more negative potential. In this regard, oxyfluorides appear unsuitable because of the higher electronegativity of fluorine. Here we show an exceptional case, an anion-ordered pyrochlore oxyfluoride Pb2Ti2O5.4F1.2 that has a small band gap (ca. 2.4 eV). With suitable modification of Pb2Ti2O5.4F1.2 by promoters such as platinum nanoparticles and a binuclear ruthenium(II) complex, Pb2Ti2O5.4F1.2 worked as a stable photocatalyst for visible-light-driven H2 evolution and CO2 reduction. Density functional theory calculations have revealed that the unprecedented visible-light-response of Pb2Ti2O5.4F1.2 arises from strong interaction between Pb-6s and O-2p orbitals, which is enabled by a short Pb-O bond in the pyrochlore lattice due to the fluorine substitution.

17.
Angew Chem Int Ed Engl ; 57(27): 8154-8158, 2018 07 02.
Artículo en Inglés | MEDLINE | ID: mdl-29737628

RESUMEN

Oxynitrides are promising visible-light-responsive photocatalysts, but their structures are almost confined with three-dimensional (3D) structures such as perovskites. A phase-pure Li2 LaTa2 O6 N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium-rich oxide precursor. Li2 LaTa2 O6 N exhibited high crystallinity and visible-light absorption up to 500 nm. As opposed to well-known 3D oxynitride perovskites, Li2 LaTa2 O6 N supported by a binuclear RuII complex was capable of stably and selectively converting CO2 into formate under visible light (λ>400 nm). Transient absorption spectroscopy indicated that, as compared to 3D oxynitrides, Li2 LaTa2 O6 N possesses a lower density of mid-gap states that work as recombination centers of photogenerated electron/hole pairs, but a higher density of reactive electrons, which is responsible for the higher photocatalytic performance of this layered oxynitride.

18.
Int Immunol ; 30(6): 255-265, 2018 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-29534174

RESUMEN

Growing evidence has revealed that the transcription factor basic leucine zipper transcription factor ATF-like 2 (BATF2) has unique transcriptional activities, including regulating cytokines via TLR signals in macrophages, which affect mortality due to infection and cancer. On the basis of genome-wide analyses using the chromatin immunoprecipitation-sequencing technique, we found that dual-specificity phosphatase 2 (Dusp2) had a significantly lower acetyl-histone status in Batf2-/- bone marrow-derived macrophages (BMDMs) compared with wild-type (WT) BMDMs. The phosphatase DUSP2 has been reported to play a critical role in inflammatory responses. Therefore, we evaluated the BATF2 transcriptional activities on the Dusp2 promoter. We found that the DUSP2 and IL-12 p40 expression levels were significantly lower in Batf2-/- BMDMs than in WT controls following their stimulation with TLR7 ligands. Further in vitro studies revealed that phospho-STAT3 was up-regulated and NF-κB p50/p65 were down-regulated in Batf2-/- BMDMs compared with their levels in WT controls. Additionally, Th1 immunity was impaired in Batf2-/- mice following their stimulation with TLR7 ligands. We also found that BATF2 interacts with NF-κB p65 and promotes DUSP2 expression through the NF-κB-binding site in the Dusp2 promoter at -203 to -121. Collectively, our findings suggest that BATF2 activates DUSP2 gene expression and up-regulates NF-κB activity via phospho-STAT3 dephosphorylation.


Asunto(s)
Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Fosfatasa 2 de Especificidad Dual/genética , FN-kappa B/metabolismo , Factor de Transcripción STAT3/metabolismo , Regulación hacia Arriba , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/deficiencia , Fosfatasa 2 de Especificidad Dual/metabolismo , Perfilación de la Expresión Génica , Ratones , Ratones Noqueados , Fosforilación , Células RAW 264.7
19.
Chemistry ; 24(69): 18204-18219, 2018 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-29570871

RESUMEN

Water splitting using a semiconductor photocatalyst with sunlight has long been viewed as a potential means of large-scale H2 production from renewable resources. Different from anatase TiO2 , rutile enables preferential water oxidation, which is useful for the construction of a Z-scheme water-splitting system. The combination of rutile TiO2 with a suitable H2 -evolution photocatalyst such as a Pt-loaded BaZrO3 -BaTaO2 N solid solution enables solar-driven water splitting into H2 and O2 . While rutile TiO2 is a wide-gap semiconductor with a bandgap of 3.0 eV, co-doping of rutile TiO2 with certain metal ions and/or nitrogen produces visible-light-driven photocatalysts, which are also useful as a component for water oxidation in visible-light-driven Z-scheme water splitting. The key to achieving highly efficient water oxidation is to maintain a charge balance of dopants in the rutile, because single doping typically produces trap states that capture photogenerated electrons and/or holes. Here we provide a concise summary of rutile TiO2 -based photocatalysts for water-splitting systems.

20.
Nat Commun ; 9(1): 772, 2018 02 22.
Artículo en Inglés | MEDLINE | ID: mdl-29472526

RESUMEN

During the last century, inorganic oxide compounds laid foundations for materials synthesis, characterization, and technology translation by adding new functions into devices previously dominated by main-group element semiconductor compounds. Today, compounds with multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offer a new materials platform from which superior functionality may arise. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of mixed-anion compounds, focusing mainly on oxide-derived materials. We devote attention to the crucial roles that multiple anions play during synthesis, characterization, and in the physical properties of these materials. We discuss the opportunities enabled by recent advances in synthetic approaches for design of both local and overall structure, state-of-the-art characterization techniques to distinguish unique structural and chemical states, and chemical/physical properties emerging from the synergy of multiple anions for catalysis, energy conversion, and electronic materials.

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